Humiseal UV40 GEL
Humiseal UV40 GEL Application
Cleanliness of the substrate is of extreme importance for the successful application of a conformal coating. Surfaces must be free of moisture, dirt, wax, grease and all other contaminants. Contamination under the coating will cause problems that may lead to assembly failures.
UV40 GEL is designed to be applied by hand syringes or automated needle dispensing such as PVA FC100 needle valve, Asymtek SC-300 in monofilament mode or other automated dispense equipment.
HumiSeal UV40 GEL may be applied by brush. The actual uniformity of the finished coating will depend on component density and operator technique. Brushed may be cleaned promptly using solvent.
To clean uncured UV40 GEL, organic solvents such as methyl ethyl ketone, t-butylacetate, glycol ether acetates etc. can be used.
HumiSeal UV40 GEL is a highly crosslinked UV cured encapsulant. The cured material has a high degree of environmental and chemical resistance and will be more difficult to remove than traditional conformal coatings. The following options are available for rework of UV40 GEL.
Thermal Removal: The most effective method for removal of UV40 GEL for selective rework applications is to burn through the cured gel directly using a hot soldering iron. The high temperature of the soldering iron (typically 300-400 ºC) softens and decomposes the gel and allows it to be easily displaced from the substrate. This allows access to the underlying solder connections for component removal and replacement. A hot air desoldering tool may also be used also. Apply heat to the desired area and the gel can be removed mechanically after it softens. Care should be taken to avoid damage to any heat sensitive components.
Mechanical Removal: This method involves the use of “micro-blasting” equipment that safely removes the cured gel by using a pressurized abrasive. After removal, the abrasive can be removed from the assembly surface without damage to the components. HumiSeal UV40 GEL has been successfully removed using the Micro-Blaster System from Comco Inc. (800-796-6626, www.comcoinc.com), but there are several companies that supply similar systems.
Chemical Removal: If the UV40 GEL has been UV cured only and not allowed to undergo any further moisture curing, HumiSeal Stripper 1072 could be used to remove the UV-cured film. Extended dwell times and periodic mechanical agitation could be required.
Refer to MSDS to insure proper storage conditions. HumiSeal UV40 GEL should be stored at 0-100 º F, away from excessive heat, in tightly closed opaque containers. Prior to use allow the product to equilibrate for 24 hours at room temperature. Since UV40 GEL is photosensitive, the product should not be exposed to direct sunlight or full spectrum fluorescent lighting. UV40 GEL is a moisture curing material and care should be taken to protect process vessels and partial containers from moisture. Partial, opened containers should be purged with a dry, inert gas such as dry air, nitrogen or argon before closure, otherwise premature polymerization by atmospheric moisture will occur.